The primary goal of the proposed study is to clarify the relationship between changes in weight and depression symptoms over time in the cohort of US adults enrolled in the Health and Retirement Study (HRS). The impact of functional status changes on the relationship between changes in weight and depression symptoms also will be assessed. This study has the following aims: 1. To determine the independent effects of (a) changes in depressive symptoms on changes in body mass index (BMI) and (b) changes in BMI on changes in depressive symptoms, after adjusting for baseline sociodemographic and behavioral factors and for changes in functional status. 2. To determine the degree to which the two relationships described above are modified by changes in functional status or other covariates. 3. To determine whether (a) change in BMI change directly affects change in depression symptom scores or whether the mechanism works indirectly through changes in functional status change and (b) change in depression symptom scores directly affects change in BMI or whether the mechanism works indirectly through functional status change. The immediate objective of the proposed research is to disentangle the relationship between weight and depression symptoms by studying the reciprocal relationship between changes in weight and changes in depression symptoms in the context of changes in functional status. These preliminary analyses will inform the development of future trials to rigorously test whether interventions targeted at reducing symptoms of depression can effectively treat obesity, whether interventions targeted at weight reduction can effectively treat depression, and whether these interventions must be tailored according to functional status. Dr. Hoffman is submitting this application as a new investigator. [unreadable] [unreadable]